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Newsmaker: A rock star on the HIV stage

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Epidemiologist, Prof. Salim Abdool Karim
Epidemiologist, Prof. Salim Abdool Karim

Medical science is fascinating – especially when the jargon is removed, and it becomes simple and engaging.

Many struggle to achieve that simplicity, but not epidemiologist Professor Salim Abdool Karim, who uses illustrations to bring clarity and simplicity to science.

Days after he and his team presented findings on three ground-breaking studies that shed light on why South Africans are so susceptible to HIV, City Press caught up with him at the Durban International Convention Centre.

Looking exhausted after chairing several sessions, he strides into the media centre with a big smile, greeting journalists and fellow scientists.

After finding a quiet space to sit, he collapses on to a chair. He admits he’s exhausted and badly in need of coffee.

He begins by talking about the first study he presented, on Tuesday – one he refers to as the Sugar Daddy study – which showed that older men were to blame for infecting so many South African teenage girls.

Several studies have found the same, but as Abdool Karim says, “this study draws the cycle of HIV transmission in South Africa”.

It shows how HIV moves from an older woman to an older man who then infects a young girl. The girl grows up, becomes a young woman and then starts dating men her age, whom she then infects. Then, that man has a side relationship with a young girl, whom he also infects.

Abdool Karim worked on the study with international and local researchers from Durban-based Aids-research body Caprisa, which includes his wife and associate scientific director, Dr Quarraisha Abdool Karim. They discovered this by studying different genetic codes of HIV in girls and young women and comparing that to those found in older men.

“We found that a vast majority of young women [younger than 25 years] with HIV had the same virus strain as men who were at least eight years older than them. About 39% of those men had the same strain as young girls. This was the virus that 30-year-old women were infected with.”

HIV has different genetic codes. It mutates as it multiplies in the body, meaning that the virus you transmit will carry different codes from the initial virus that infected you.

While this study gives concrete evidence that sugar daddies or “blessers” drive high HIV prevalence in young girls, it’s the two other Caprisa studies that have provoked another debate and set scientists on a new path to find ways to prevent HIV infection in girls and young women.

The studies found that an imbalance in vaginal bacteria increases the risk of HIV infection in women and can also interfere with the effectiveness of pre-exposure prophylaxis (or PrEP: the antiretroviral (ARV) drugs given to HIV-negative people to prevent infection).

Both studies followed the 2010 Caprisa 004 study that showed a gel containing 1% of the ARV drug tenofovir can reduce the risk of HIV infection by about 40%. Researchers went back to analyse the vaginal bacteria to establish why the gel was only effective in some women.

“In one study, we investigated the genetic codes of vaginal bacteria of 119 women and found that they had an overgrowth of Prevotella bivia in the vagina. This bacterium increased their chances of HIV infection thirteenfold compared with those with low levels or an absence thereof,” Abdool Karim said.

In the third study, vaginal swabs from 688 women were analysed and researchers found that the vaginal bacteria imbalance – where healthy bacteria levels were low or absent – not only increased the risk of HIV infection, but interfered with the effectiveness of PrEP.

Laboratory studies showed the bad bacteria gobbled up tenofovir. What was more interesting, says Abdool Karim, “was how quickly [bad bacteria] Gardnerella vaginalis absorbed tenofovir”.

“It took a mere four hours for the bacterium to consume tenofovir, meaning that this is what could have led to the reduced effectiveness level of the gel in some women,” he said.

This, Abdool Karim says, “paves the way for integrating PrEP with sexual and reproductive health services”.

“These findings tell us that vaginal pH testing is important when initiating PrEP.”

If the vagina’s pH level is above 4.5, antibiotics should be administered to “promote a healthy vagina”.

Caprisa is now conducting a PrEP study in KwaZulu-Natal that is being amended to assess whether bacterial vaginosis screening and treatment improves PrEP efficacy.

Abdool Karim won’t be drawn on predicting what the study will find, only saying that “the next conference in 2018 should be interesting”.

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